WATKINS GLKN 



395 



Fig. 9. Step Fall in Enfieid (Butternut) Creek, southwest of Ithaca, illustrating 

 the influence of horizontal strata on waterfall form. 



sandstone layers retard erosion and form falls, sometimes single leaps, 

 sometimes step falls (Fig. 9) where the water cascades from ledge to 

 ledge. With the variable spacing of the sandstone and shale layers, 

 there is almost infinite variety in waterfall form. 



The variation in gorge and waterfall form is still further in- 

 creased by the joint planes which cleave the strata nearly vertically, 

 and thus introduce a cause for vertical variation in erosion in addi- 

 tion to the horizontal. Some of the most beautiful of the cascades 

 are those where the stream erosion has etched out combinations of 

 horizontal and vertical irregularity in the rock bed over which the 

 water falls (Fig. 8). The joint planes often guide the stream course 

 between the falls also, sometimes confining it between narrow, canyon- 



